1. Field of the Invention
The present invention relates to a method and apparatus for installing pipe and a control line in a well. More specifically, the present invention relates to a method and apparatus for securing a control line to a string of pipe as the pipe is being made up and run into a well.
2. Background of the Related Art
Wells are generally drilled deep into the earth's crust to establish fluid communication between the surface and sub-surface geologic formations containing naturally occurring hydrocarbon deposits, such as oil or gas. A well provides a fluid conduit allowing subsurface deposits of oil and gas to be produced at the surface. It is common for a drilled borehole to penetrate a plurality of formations. Formations may contain hydrocarbons or other fluids of different compositions and at different pressures than the hydrocarbons and fluids contained in other formations. Formations may also contain water (aquifers), brine, hydrogen sulfide gas and other materials that may be undesirable.
A drilled borehole is completed into a well by circulating cement into the annulus between the wall of the drilled borehole and the outer surface of a pipe string called casing to form a cement liner. The cement hardens to isolate penetrated formations from flowing into the well and to the surface. Once a borehole is drilled and completed, decisions are made as to which of the penetrated formations to selectively produce. A perforating tool is used to cut a hole through the casing and the cement liner to selectively establish fluid communication between the targeted formation and the surface. Once a formation is perforated, the well may be produced to (pressure) depletion, until it “waters out” by increasing water content, or both. Once a formation is depleted or watered out, it may be desirable to intervene in the well to alter or isolate the formation so that other formations may be perforated and produced without the production being burdened by fluid losses into depleted formations or by water intrusion from watered-out formations. Intervention is generally performed by wire line unit (WLU) workover, coiled tubing unit (CTU) workover or by a conventional workover rig. A WLU or CTU workover is performed by lowering an instrument or tool into the well using a specialized rig having a long spooled wire line or tubing for connecting or controlling the downhole instrument or tool from the surface. The conventional workover rig generally requires that all production tubing be removed from the well so that tools or instruments may be run into the well on a work string.
If the depleted or watered-out formations are lower in the well than the formation, the depleted or watered-out formation may be isolated from the well by using one of the three conventional intervention techniques described above. In a conventional intervention workover, material such as cement or sand may be deposited into the bottom of the well to form a plug to seal off the perforations in the depleted or watered-out formation, and to thereby isolate the depleted or watered-out formation from the new formation located above. Once a sand or cement plug is in place, another workover may be required to later remove it. Packers are tools that can be installed in a well during a workover to isolated, depleted or watered-out formations.
Conventional workovers to install or remove downhole plugs or packers are unnecessary if formations can be isolated or remotely controlled using downhole devices. Downhole devices, such as valves or chokes, may be installed in a pipe string as it is being made up and run into a well to enable the selective production, isolation or flow-control of fluids residing in the formations penetrated by a well. Surface-controlled downhole valves or chokes require continuous control lines that extend from the surface through the well to the depth at which the downhole devices are installed in the pipe string. Control lines must be installed as the pipe string is being made up and run into the well.
Continuous control lines are generally stored and transported to the rig location on spools. The spools of control line are generally mounted on a horizontal axle on or near the rig floor so that the control line may be easily and smoothly “fed” to and fastened to the pipe string by reeling of the spool.
Oil and gas wells may be equipped with control lines for electrically, hydraulically or optically linking various downhole devices to the surface. Control lines may be used to receive data from downhole instruments and to selectively operate from the surface downhole devices such as valves, switches, sensors, relays or other devices. One use of control lines is to open, close or adjust downhole valves in order to selectively produce or isolate formations at locations deep in the well. A control line may transmit downhole data to the surface and communicate commands to the same or other downhole devices. The control line may comprise conductive wires or cables for electrically controlling downhole devices, fibers for optically controlling downhole devices, or small-diameter tubing for hydraulically controlling downhole devices. Control lines are generally of a small diameter relative to the diameter of the pipe string to which they are secured, and are generally between 0.5 and 6 cm in diameter. Control lines may be bundled to make a single umbilical with diameters of 10 cm or more. Control lines are generally secured along the length of the outer surface of a pipe string, generally parallel to the center axis of the bore of the pipe string. Continuous control lines are secured to the pipe string and installed in the well as joints of metal pipe are made up into a pipe string and run into a well. Control lines secured to pipe string are subject to being damaged and made useless if pinched or crushed by pipe slips used to grip and support the pipe string, such as during the process of making up the pipe string and running it into the well.
A spider is a device used on a drilling or workover rig for gripping and supporting the pipe string as joints of pipe are made up into the pipe string. The spider has an interior bore, generally aligned with the pipe string, through which the pipe string passes. The spider has a circumferential arrangement of radially inwardly movable pipe slips disposed around the pipe string and within the internal bore. The pipe slips move radially inwardly to grip the outer surface of the pipe string and support the pipe string in the well when the pipe string is not supported by the lift elevator. It is important that the pipe slips in the spider uniformly engage and grip the pipe string in order to prevent crushing or damaging the pipe making up the pipe string. Each pipe slip within the internal bore of the spider applies a force radially inwardly against the outer surface of the pipe string. It is important that the pipe slips are concave around the pipe in order to contact the pipe over as large an interval as possible in order to minimize the localized stress imposed on the pipe by the pipe slips.
If a control line becomes pinched or trapped between the pipe slips of the spider and the outer surface of the pipe string, or if a control line is pinched between adjacent segments of the pipe slips as they move around and radially inwardly to contact the pipe string, the control line may be damaged and surface control of downhole devices or data transfer from downhole instruments may be lost or impaired. It is important that the method used to secure control lines to the pipe string be designed to prevent control line damage.
In many installations, it is desirable to secure multiple control lines along the length of the outer surface of the pipe string in order to allow surface control of multiple downhole devices. For example, the tools and other control valves or instruments requiring control lines may be made up into the pipe string at various depths, and the number of control lines at any given point on the pipe string depends on the location of that point in the pipe string. Multiple control lines are especially useful in deep offshore wells that penetrate multiple formations. Existing designs may require four or more control lines for each string of pipe that is run into the well. Multiple control lines are most efficiently made, stored, transported and installed in bundles comprising control lines coupled together in a generally parallel, side-by-side configuration. Multiple control lines may require larger clamps to secure the bundle along the length of the outer surface of the pipe string.
A method has been developed for securing control lines to a pipe string as the pipe string is made up and run into a well. U.S. Pat. No. 6,131,664 (“the '664 Patent”) is directed to using an elevated work platform constructed on the rig floor. The work platform is equipped with hydraulic tongs for making up the pipe string, and an opening above the well in the floor of the work platform that is generally aligned with the well and with an opening in the rig floor beneath the work platform. The work platform disclosed in the '664 Patent supports the spider and, when the pipe string is supported by the spider, the work platform must support the weight of entire pipe string. This requires the work platform to be built to support 200 tons or more. The work platform described in the '664 Patent must also provide sufficient work area for rig personnel to use the tongs to make up joints of pipe that are lowered and aligned in position above the pipe string to be threadably made up into the pipe string.
The '664 Patent discloses that control lines are provided to the pipe string from a separate work area maintained on the rig floor and below the level of the work platform. The control lines are stored on and continuously provided from spools located lateral to the pipe string and adjacent to the opening in the rig floor. Clamps are installed by rig personnel working in the work area beneath the work platform to secure the control lines to the pipe string. One problem with the method and apparatus for installing control lines described in the '664 Patent is that the control lines and spools themselves take up a significant area of the rig floor and present an obstacle to various operations.
What is needed is a method of safely securing control lines to a pipe string as the pipe string is being made up and run into a well. What is needed is a method and an apparatus that enables the safe and inexpensive installation of control lines that are being secured to a pipe string as it is made up and run into a well. What is needed is a method of securing control lines along the length of a pipe string as it is being made up and run in a well that eliminates obstructions to escape routes to be used by rig personnel in the event of a well blowout or other well control situation.